It depends on your career ambitions.
Don't get me wrong, Warwick's course is a good course, but it generally does not make sense for prospective accountants to go to university when there's a more direct, relevant, cheaper, and quicker path to qualification i.e. through the accounting bodies themselves. You can get a second opinion from professional accountants in the field regarding this.
If you want to get a degree, Warwick is a good university to apply to, as any graduate from most universities can vouch for. It's also one of the targeted universities by top end accounting firms for graduates. However, the employers won't specifically be looking for accounting graduates as opposed to just any decent graduate from the university. It's also a good place to network with people who are either going into the same field as you or in different fields. As anyone can vouch for when it comes to job hunting, networking is half the battle when it comes to getting a job (especially a good one).
What I am saying is that requiring A Level Maths is a bit of an overkill for accounting, since it's not necessary in accounting qualifications (to my knowledge). However, if you want to go for Warwick's course then I would recommend spending a gap year to do the A Level as a private candidate. Haing said that, I am a fan of maths and I like the A Level, so I am biased.
Unfortunately, Warwick's degree course with the foundation year also require you to have Maths, Further Maths, and/or Physics as well as come from a certain background. In other words, you would need to do either A Level Maths or Physics during a gap year to get onto the course anyway. See the following:
https://warwick.ac.uk/study/undergraduate/courses/accountingandfinancefoundation/